Atrophotergum silvaticum, Mesibov, Robert, 2004

Mesibov, Robert, 2004, A new genus of millipedes (Diplopoda: Polydesmida: Dalodesmidae) from Tasmania, Australia with a mosaic distribution, Zootaxa 480, pp. 1-23 : 8-9

Atrophotergum silvaticum n. sp.

Figs. 1 , 3 , 4, 6 ; map Fig. 12

Holotype: Male, Winter Brook, Tasmania, DQ154107 (41°27’02”S, 145°59’13”E), 660m, 28.v.1995, R. Mesibov, QVM 23:25493.

Paratypes: 3 males, details as for holotype, AM KS87137; 4 males, 1 female, details as for holotype, QVM 23:25280; 4 males, Flowerdale River, CQ838645 (40°57’44”S, 145°37’08”E), 90m, 17.v.1995, R. Mesibov, QVM 23:25279, 1 dissected; 6 females, same details, QVM 23:25310.

Other material examined: 44 males and 17 females. See Appendix for details.

Diagnosis: Distinguished from other Atrophotergum spp. by the unique form of the gonopod.

Description: As for genus. Males 8–9 mm long, 0.7–0.8 mm in maximum vertical diameter. In alcohol, most specimens are light tan with reddish antennae; occasional more deeply coloured specimens are darker tan with lighter paranota. Dark patches are often visible near ozopores; in some cases these appear to arise from tissue staining (possibly by the defensive secretion), in other cases tissue has retracted from transparent cuticle revealing dark­coloured gut contents.

Gonopod telopodite ( Fig. 6 ) flexed posteriorly at about one­third its length. Solenomerite a strap­like process extending posterodistally and curving laterally from the anterodistal corner of the SF; the process divided near its tip into a flattened anterior portion containing the terminus of the prostatic groove and a shorter, blunter, posterior branch. PDC produced as a finger­like process, slightly curved and parallel to the solenomerite, but not extending distally as far as the solenomerite tip; PBC bent laterally in a smooth curve. TT bent slightly laterally, not extending distally as far as the tip of the process arising from the PDC. MES in two parts: a short, rod­like, pointed process resembling the TT but shorter and narrower, more or less parallel to the long axis of the telopodite; and a much stouter, blade­like process curving posteriorly and laterally. LES flexed slightly mesally, with its distal edge angled so that the blunt, thickened anterior corner is considerably more distal than the posterior corner. The curvature of the LES and the longer process of the MES are such that they cross, with the MES process terminating anterior and slightly basal to the LES.

Anterior sternal process on somite 17 ( Fig. 4 D) a low eminence; the anterior portion of the posterior process a low ridge, somewhat excavated mesally, the posterior portion a short, finger­like structure directed ventrally.

Distribution and habitat: Locally abundant in leaf and woody litter in coastal scrub, wet eucalypt forest and Nothofagus rainforest over ca. 9000 km 2 in northwest Tasmania, from sea level to at least 870 m ( Fig. 12 ). Also found in forest plantations ( Bonham et al. 2002 [as ‘genus A, sp. 1’]; Mesibov, unpublished results).

Etymology: Latin silvaticus, of forests, adjective.

Remarks: A. silvaticum is somewhat variable in size and colouration. It has probably been collected as females and juveniles from more localities than are shown in Fig. 12 , but it has so far not been possible to distinguish these specimens from similar, co­occurring dalodesmids.

Figures

FIGURE 1. Atrophotergum spp. details. Setation and antennal apical cones not shown; drawings not to same scale. (A) Dorsal view of trunk of A. montanum n. sp. emphasizing metatergites; male from QVM 23: 25316; (B) antenna, (C) somite 12, (D) leg 6 (somite 6) and (E) leg 19 (somite 12) of A. silvaticum n. sp.; male from QVM 23: 25286; (F) anterior view of somite 6 showing leg 6 (left) and leg 7 (right) of A. montanum n. sp.; male from QVM 23: 25322; (G) posterior view of somite 3 of A. montanum n. sp.; female from QVM 23: 25345.

FIGURE 3. Ventral SEM views of right side of somite 2 of male Atrophotergum spp., anterior to the right. Scale bar = 0.20 mm in both cases. (A) A. silvaticum n. sp., specimen from QVM 23: 25286, showing typical form of pit; (B) A. sodalis n. sp., QVM 23: 25385, showing shallow ventral excavation.

FIGURE 6. Gonopod of A. silvaticum n. sp. Mesal (left) and lateral (center) drawings of left gonopod telopodite of male from QVM 23: 25286. Lateral and slightly ventral SEM (right) of right gonopod telopodite of another male from QVM 23: 25286. Setation not shown in drawings; dashed line marks course of prostatic groove.

FIGURE 12. Known localities in Tasmania of Atrophotergum bonhami n. sp. (open squares), A. montanum n. sp. (filled squares), A. pastorale n. sp. (crosses), A. silvaticum n. sp. (filled triangles), A. sodalis n. sp. (filled circles) and A. wurrawurraense n. sp. (open triangles). The top map shows overall distributions, while the bottom map shows localities and major streams within the rectangular area marked on the top map.